11 replies to this topic

[SnowMonkXV]

First off, I'll post a picture of my rig for reference if it is needed.



I'm in the final run of a personal Quad-Rayven build. I'll be throwing together a somewhat detailed writeup upon completion for those who are interested.

My Issue. Just in base testing, this thing has an absurd amount of power, which, in-essence is what I was looking for. However, I do intend on using this in a matter of ways, and being having the ability to 'tone-down' this blaster would be of great value. So, I'm looking to add a selector of some type to change the power of the second motors in my setup, to run at lower power, or max at its as needed. A basic Hi/Lo if you will. I have seen blacklion's Solution on his stryfe, ( http://nerfhaven.com...showtopic=23959 ) however, I'm slightly short on space and am looking for ideas of something much smaller.

The primary motors are simply overvolted stocks, secondaries are Mach-Dash Pro's, running 2 paralleled Efest IMR 14500's. ( http://www.ebay.com/...984.m1497.l2649 )

I was hoping I could simply install some resistors on a secondary circuit, and just use a switch select between the two, however the motors fail to get the required power and fail to turn at all.
A second thought is to use something like this, similar to blacklion's ( http://www.ebay.com/...984.m1423.l2649 ), however then I will require another battery source in an already cramped shell. I'm also running for a clean outside appearance once completed, so with all do respect, not needing a large knob would be great.
I've also considered a completely different circuit running the motors in series, however the added wiring and circuit re-routing deems that an unwanted and last resort option.

Any advice on this? There may vary well be something simple I'm just failing to realize as a solution, (to many hours/days straight on this ) which is why I'm reaching out for assistance.

My forward Thanks to any ideas, and I can test low tech solutions on the spot as necessary.

[azrael]

Use diodes in series with the power supply to reduce the voltage. Make them switchable.
http://www.reddit.co...ng_help/cdbb387

[MAV13]

You could hook up a PWM controller, although I've only see those go down to 6V minimum, which is more than the Mach Dashes should take.

[SnowMonkXV]

See, that is what I was talking about. I never even considered using diodes. They would work perfect for this setup. Now I just need to determine the size and capability of the diodes. And see if my local Radio-shack has such diodes....

I shall see what I can find. Thanks!

[azrael]

'SnowMonkXV', on 12 Nov 2013 - 11:56 PM, said:

See, that is what I was talking about. I never even considered using diodes. They would work perfect for this setup. Now I just need to determine the size and capability of the diodes. And see if my local Radio-shack has such diodes....

I shall see what I can find. Thanks!

1N5400 diodes are perfect for high current applications like these. Sorry, should have mentioned that model haha. Any of the diodes from that series will work well.

[Hammy]

Can also use 1N4001, it's a silicon diode designed for power supplies.
Voltage drop will be approx 0.7V

Anyway (regardless of part number) if it is a silicon rectification diode, the voltage drop will be approx 0.7 V. Just need to choose one that can take the intended amps.
And you can parallel them up to increase the amps if you so desire.

[azrael]

Just remember it's not so simple, diode's forward voltage depend on the amount of current being pulled. Check out the charts.
Surge/burst current for a 1N400X series is 30A, but the continuous is much lower, at 1A. It might not work well, depending on how much current is being drawn. I think I remember my Mach Dashes pulling maybe 3-5A continuous.

I doubt parallel will work all that well. It works for resistors, but in a circuit using series diodes, one diode will conduct before the other due to tolerance mismatches in their forward voltage. You may never see excess heat dissipate through the secondary diode.

Edited by azrael, 13 November 2013 - 07:45 PM.

[SnowMonkXV]

As suggested, two 1N5400's in series worked absolutely perfect, both in size, ease of install, and amount of power drop. Now to get something for my LED's. However, I feel I may try to find a potentiometer for those, I'd rather like to have a wider range over dim/bright.


A Grateful Thank You as Well!

[azrael]

Awesome! Radioshack should have a pot with an integrated SPST switch. This would be perfect for LEDs, so you can turn them off all the way.

Make sure to have a minimum resistor in series with the pot to prevent it from blowing up the LEDs haha

[SnowMonkXV]

Surprisingly, not so much. My Accessories power source is 4.5V (3 AAA), and my main LED's which I'd like to have control over are rated at 2.2V. Now, I already have a resistor for each LED as I'm running them Parallel, which could count as the minimum, however finding at POT rated that low, or at a usable size,is proving difficult, unless I special order....

Meh, its low on the priority list right now.

[azrael]

'SnowMonkXV', on 16 Nov 2013 - 4:02 PM, said:

Surprisingly, not so much. My Accessories power source is 4.5V (3 AAA), and my main LED's which I'd like to have control over are rated at 2.2V. Now, I already have a resistor for each LED as I'm running them Parallel, which could count as the minimum, however finding at POT rated that low, or at a usable size,is proving difficult, unless I special order....

Meh, its low on the priority list right now.

finding a pot rated that low? Heh? Any 1/4W potentiometer will work just fine.

I don't recommend running them in parallel, only because the forward voltages will vary a tiny bit with each LED. You can measure them for perfect matching, or just get lucky, like I did when I built my halloween costume.
If they each have independent resistors, you'll get a more even lighting, or could at least compensate.

What's a "usable size"? I know Radioshack's huge, but a 9mm pot would be pretty good. They're not expensive. I buy them from smallbearelectronics when I buy stuff for guitar tech work.

[SnowMonkXV]

'azrael', on 16 Nov 2013 - 7:08 PM, said:

finding a pot rated that low? Heh? Any 1/4W potentiometer will work just fine.

I don't recommend running them in parallel, only because the forward voltages will vary a tiny bit with each LED. You can measure them for perfect matching, or just get lucky, like I did when I built my halloween costume.
If they each have independent resistors, you'll get a more even lighting, or could at least compensate.

What's a "usable size"? I know Radioshack's huge, but a 9mm pot would be pretty good. They're not expensive. I buy them from smallbearelectronics when I buy stuff for guitar tech work.

Yes, I've got about a dozen LED's all with individual resistors for each light, and was planing on using a Pot. right after my power source to act as a switch, as well as a dimmer. This has been on delay, however I'll see if they have anything later today.